Support is requested for an intensive one-week Summer workshop on the histopathobiology of neoplasia for graduate students, postdoctoral trainees, and senior scientists engaged in basic cancer research. Trainees in basic science fields related to oncology are heavily committed to highly specialized studies, either bench or field work, and are unlikely to have had the time or opportunity to pursue courses of study in normal histology or tumor pathobiology. This workshop responds to this need by providing participants with a background in cancer biology, pathology, and related disciplines that will enable them to return to their laboratories and pursue investigations that will contribute to our understanding of the etiology, prevention, and treatment of cancer. At least one such workshop has been held every summer since 1978. The workshop program consists of 28 hours of laboratory sessions, II hours of lectures, and at least 4 hours of poster sessions. The faculty consists of 16 outstanding cancer researchers from pathology and other appropriate scientific disciplines. The American Association for Cancer Research (AACR), the oldest nonprofit professional society in the cancer field with a membership of nearly 8,000 laboratory and clinical cancer researchers, will assume the overall administration of this workshop. The AACR has the necessary resources and expertise to assist the experienced faculty with the recruitment of students and new faculty and with administrative details. The workshop will continue to be held at its original site, the excellent conference facility at the Keystone Center.